This invention relates to apparatus for mounting a document feeder on a copier/duplicator for movement between a position adjacent an exposure station of the copier/duplicator and a position spaced from the exposure station.
It is known to provide a document feeder for a copier/duplicator and to mount such a feeder for pivotal movement relative to the exposure station of the copier so that the exposure station is accessible for copying of individual document sheets, books, or the like. See, for example, commonly assigned U.S. Pat. No. Re. 27,976 which issued on Apr. 23, 1974 in the name of L. W. Sahley entitled DOCUMENT FEEDER (e.g., column 5, lines 42-51 and column 6, lines 37-44), and commonly assigned U.S. Pat. No. 4,169,674 which issued Oct. 2, 1979 in the name of Matthew J. Russel entitled RECIRCULATING SHEET FEEDER (e.g., column 7, lines 47-52). As viewed from the front of the machine, the Sahley document feeder swings in a counterclockwise direction away from the exposure station and the Russel feeder swings upwardly from the front of the machine about an axis located along the rear of the machine.
Pivotal mounting of document feeders and counterbalancing apparatus therefor also are disclosed in U.S. Pat. Nos. 4,097,145 issued June 27, 1978 in the names of H. E. Luperti et al., and 4,135,805 issued Jan. 23, 1979 in the names of T. N. Taylor et al. Also, a counterbalance mechanism for a document feeder hinged at the back of the copier is disclosed on pages 109 and 110 of the March 1980 edition of Research Disclosure, Item 19119. Research Disclosure is published by Industrial Opportunities Ltd., Homewell, Havant, Hampshire, P09 1EF, United Kingdom.
When feeders are pivoted at the rear of the copier, as disclosed in U.S. Pat. No. 4,169,674, raising of the feeder makes a large area of the platen available for receiving individual document sheets, books or the like that are to be copied. However, when feeders are pivoted at the side edge of the platen (as viewed from the front of the machine) as disclosed in U.S. Pat. No. Re. 27,976, the pivot axis of the feeder normally is near the platen in order to reduce the force required for lifting the feeder and the associated problem of counterbalancing the weight of the feeder. Such placement of the pivot axis leaves very little room at the side edge of the platen adjacent the platen for correctly and conveniently positioning a book for copying. This problem is magnified when the center of the book between two pages is to be positioned along the edge of the platen near the pivot axis. While the single pivot can be extended outwardly away from the edge of the platen, this increases the force required to lift the feeder and also increases the counterbalancing forces. Document feeders may be heavy (e.g., about 60 pounds). Therfore, it is important that much of the weight of the feeder be balanced so that the feeder can be moved between its various positions in response to a light force applied by the machine operator.
It is known to move a member about two pivot axes. For example, U.S. Pat. No. 4,098,429, issued July 4, 1978 in the name of A. M. Hodge for TRASH CONTAINER LID SYSTEM, discloses a trash container with a lid adapted to cover an open end of the container. The lid is moved about one pivot axis to a "stabilized", partly open position to receive trash or other material through the open end of the container. When the container is in the upright position, the lid cannot move beyond its party open or "stabilized" position due to the presence of stops which limit movement of the lid. A counterweight in the lid tends to hold the lid in the open or "stabilized" position. When the container is to be emptied, the container is inverted and the lid moves about a second pivot axis to a fully opened position to allow the contents of the container to be removed by gravity.
Thus a document feeder mounted for movement about an axis at the side of a platen (as viewed from the front of the machine) should be mounted so that when the feeder is in its open position there is a substantial area along side of the platen adjacent to the feeder to accommodate a portion of a book (or other thick document) that is to be placed on the platen for copying. In addition, the feeder should be counterbalanced in such a way that it can be swung from its lowered position to its elevated position and back to its lowered position with a minimum amount of effort by the machine operator. The mounting and counterbalancing problems discussed above are overcome by the present invention.